Fundamental Study on Morphology Control of Polymer Alloys in an Electric Field.

悬浮在电介质中的液滴在相对低的电场下变形为椭球体，但在高电场下破裂。这一现象表明，聚合物合金的形态，特别是聚合物共混物的形态可以用电场控制的可能性。本文研究了十六烷基三甲基溴化铵（CTAB）和水杨酸钠（NaSal）水溶液以及聚丙烯酰胺（PAA）水溶液悬浮在聚二甲基硅氧烷（PDMS）介质中的粘弹性液滴在电场中的变形。在一片交流电场下。10^5 Vm^<-1>时，液滴变形为具有由（X-Y）/（X+Y）定义的变形度D的椭圆体，其中X和Y分别是椭圆体的长半轴和短半轴。D对时间对数的曲线是双阶S形，其特征在于有两个延迟时间。在短时间区域的变形归因于弹性变形， ...更多信息 电应力和液滴弹性之间的平衡。随着经过时间的增加，在液滴中发生应力松弛，因此液滴进一步变形，直到其达到由电应力和界面张力之间的平衡给出的平衡变形。理论上，快速过程的变形量D_F和延迟时间τ_F的理论计算公式为：D_F =（9 ε K_2E^2/16）（γ/B + 5G/4）^<-1>（1）τ_F τ_F = eta_2/（G + B/γ）（2）式中，K_0为真空的绝对介电常数，K_2为介质的相对介电常数，E为电场，G为准平衡剪切模量，E为真空的相对介电常数，G为真空的相对介电常数。γ，界面自由能; B，液滴的半径B;以及eta_2，介质的粘度。观测到的D_F和τ_F近似符合方程（1）和（2）。用粘性液滴理论近似地解释了慢过程的行为。然而，平衡变形比理论值大1.4倍。D的时间依赖性通过由麦克斯韦元件和Voigt元件的并联组合组成的力学模型来建模。少

A droplet suspended in a dielectric medium deforms into an ellipsoid under a relatively low electric field but bursts under a high electric field. This phenomenon suggests a possibility that morphology of polymer alloys especially that of polymer blends could be controlled with an electric field. In this study deformation of viscoelastic droplets in an electric field of was studied for droplets of aqueous solution of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) and those of aqueous poly(acrylamide) (PAA) suspended in media of poly(dimethyl siloxane) (PDMS). Under an AC field of calpha. 10^5 Vm^<-1>, the droplet deformed into an ellipsoid with a degree of deformation D defined by (X-Y)/(X+Y) where X and Y are the major and minor semiaxes of the ellipsoid, respectively. The D versus logarithm of time curve was double-step sigmoidal and was characterized with two retardation times. The deformation in the short time region was attributed to an elastic deformation due … More to a balance between the electric stress and the elasticity of the droplet. With increasing elapsed time, stress relaxation occurs in the droplet and hence the drop deforms further until it reaches an equilibrium deformation given by a balance between the electric stress and the interfacial tension. Theoretically, the magnitude of deformation D_F and the retardation time tau_F for the fast process are calculated theoretically as follows:D_FF = (9epsilon_oK_2E^2/16)(gamma/b + 5G/4)^<-1> (1) tau_F tau_F = eta_2/(G + b/gamma) (2) where epsilon_O is absolute dielectric constant of vacuum; K_2, the relative dielectric constant of the medium; E, the electric field; G, the quasi- -equilibrium shear modulus; gamma, the interfacial free energy; b, the radius b of the droplet; and eta_2, the viscosity of the medium. The observed D_F and tau_F agreed approximately with equations (1) and (2). The behavior of the slow process were also explained approximately by the theory of a viscous droplet reported previously. However, the equilibrium deformation was 1.4 times larger than the theoretical value. The time dependence of D was modeled by a mechanical model composed of parallel combination of a Maxwell element and a Voigt element. Less